Thermoplastic yarn plasticizing device and method of plasticizing thermoplastic yarn

ABSTRACT

A yarn heater constructed so that when used with a false twist device, a coaction between heater and spindle is created when plasticizing fluid is caused to spin within the heater in the direction in which the false twist device is inserting twist in the yarn.

United States Patent 1191 Conrad July 3, 1973 [54] THERMOPLASTIC YARNPLASTICIZING 3,031,770 5/1962 Caithens, Jr. et a1. 28/62 UX DEVICE ANDMETHOD OF PLASTICIZING 3.206.922 9/1965 Nagahara et al 57/34 X 13,217.482 11/1965 Baer 28/l.3 X THERMOPLASTIC YARN 3,303,546 2/1967 AVan Blerk.... 28/l.3 [76] Inventor: Robert F. Conrad, 5341 Falmouth3,340,684 9/1967 Shichman 57/34 Road, Washington, D.C. 20016 3,380,2424/1968 Richmond et a1. 57/157 X [22] Filed: June 25, 1969 I App] 862,097Primary Examiner-Stanley N. Gilreath Related US. Application DataDivision of Ser. No 656,223, July 26, 1967, abandoned.

US. Cl. 57/l57 TS, 28/62, 57/34 HS 1m. (:1 D02g 1/02 References CitedUNITED STATES PATENTS 11/1959 Bley 57 34 X Assistant Examiner-Werner H.Schroeder Attorney-Shaffert and Miller 1 1 ABSTRACT A yarn heaterconstructed so that when used with a false twist device, a coactionbetween heater and spindle is created when plasticizing fluid is causedto spin within the heater in the direction in which the false twistdevice is inserting twist in the yarn.

3 Claims, 9 Drawing Figures mmmm ms 3.742.695 v sum 2 or z v INVENTOIRolelf F. (M86 THERMOPLASTIC YARN PLASTICIZING DEVICE AND METHOD OFPLASTICIZING THERMOPLASTIC YARN This is a division of application Ser.No. 656,223, filed July 26, 1967, now abandoned.

This invention relates inter alia to a thermoplastic yarn plasticizingdevice, hereafter referred to simply as heater, wherein thermoplasticyarn may be subjected to the action of plasticizing fluid such as steamor hot air at elevated pressures and temperatures, and in amanner whichresults in increasing the effectiveness of yarn heaters per unit oflength. This is accomplished, for example, by providing a heater havinga yarn passageway in which at an intermediate location along its lengtha plasticizing fluid under pressure is introduced. The yarn passagewayon either side of this location has a capillary diameter. This diameteris preferably larger than the diameter of the yarn passing through theheater but less than 0.02 inches for yarns of 200 denier or less. Thecapillary passageways act as seals on either side'of the location atwhich the plasticizing fluid under pressure is maintained and meter itsescape to a degree that it becomes-practical to use steam and hot air atelevated pressures as the plasticizing fluid and yet not seriouslyinterfere with texturing operations such as, for example, themodification of torque stretch yarn into set" yarn. Furthermore thecapillary passageways are so small that the plasticizing fluid and yarnpassing through are so confined together and moved relatively that anefficient heat transfer is obtained between them. Thus, even though theyarn is subjected to the highly effective action of a plasticizing fluidunder pressure, a-comparatively small quantity of heated fluid isdischarged into the surrounding atmosphere and yet the yarn issatisfactorily.plasticized because the small quantity of fluid whichis-heated is efficiently utilized. The heater also includes means foradding heat energy to the expanding fluid passing through one or both ofthe capillary seals, so that when desired or needed more heat may betransferred to the yarn. It is also contemplated-that the heater may beinsulated to improve its performance and may also have associated withit controls of the kind which regulate the supply of energy to theheater to offset the effect of changes in ambient temperatures (and/orline voltage in the case of electrically energized systems).

The incorporation of a heater as described above into thermoplastic yarntexturing operations such as falsetwisting, heat treating of torquestretch to make set yarns, and other thermal processing, involves novelmethods and apparatus which are also described hereinafter. For example,one modification of a heater of the kind dealt with herein isconstructed so that when used with a false twist device a novel coactionbetween heater and spindle is created to thus provide a new type offalse twist apparatus and method. Specifically plasticizing fluidflowing along the yarn path within the heater is caused tospin in thedirection in which the false twist device is inserting twist in theyarn, thus facilitating the action of the false twist device ininserting twist in the yarn.

It has been recognized since shortly after the introduction of nylon inabout I938 that steam, especially saturated steam under pressure has aplasticizing effect upon nylon above that which could be attributed toits temperature alone. This fact was utilized in the first commercialprocess for making torque stretch yarn which involved as one step thetreatment of twisted autoclave. At least a decade earlier it had been,visualized that false-twisting might be used to provide a continuousprocess for making a type of textured (woollike) yarn (See U.S. Pat. No.2,089,239 to Whitehead) and efforts were made to adapt such a processfor the continuous manufacture of torque stretch yarn (See U.S. Pat. No.2,790,298 to Kunzle). However, no practical way of using steam underpressure in a falsetwisting process was devised, and the manufacture oftorque stretch yarn by a continuous false-twist process did not become acommercial reality until the introduction of the false-twist machineshown in Seem and Stoddard U.S. Pat. Nos. 2,803,108 and 2,803,109 whichmade use of so-called dry heat and embodied a yarn plasticizing heaterwhich was constructed and controlled to give a performance which becamethe standard for all commercial false-twist equipment up :to the presenttime, that is one capable of maintaining the dry heat temperature towithin i 1 percent in F. Al-

though it is still generally recognized that steam under pressure, withits dual plasticizing effect, is a preferable medium for plasticizingthermoplastic yarns, all modern false-twist machines neverthelesscontinue to employ so-called dry heat.

One of the objects of this invention'is to. provide methods andapparatus which make possible the use of steam as a plasticizing mediumin continuous false-twist processing of thermoplastic yarn and in themanufacture of set yarn from torque stretch yarn.

Following the advent of the Seem and Stoddard machine variousimprovements were made in the components of false-twist machines whichallowed operation at a rate of yarn through-put up to about l20-l 40yards per minute. As operating speeds were increased the length of yarnheater was also increased; and in present-day machines a heater lengthof 3 feet or more is not uncommon. Machines with heaters of this lengthare awkward to service and operate because of their overall height, orbecause some machine functions are incorporated into a separateapparatus located nearby to avoid excessive overall height. One of theobjects of the present invention is to provide a straight-through heaterdesign which is more effective per unit of length and thus again permitsa rational design of yarn processing equipment capable of high speedoperation.

FIG. 1 is a vertical sectional view of one form of heater according tothe invention;

FIG. 2 is a greatly enlarged detail of a modification of a capillaryseal for use in the heater wherein the yarn passing therethrough istwisting, as for example in a false twisting operation;

FIG. 3 is a schematic diagram of a false twisting machine which includesa heater system according to the invention;

FIG. 4 is a vertical cross sectional view through a fonn of deviceuseful for heating one or both of the capillary seals of a heater;

FIG. 5 is a schematic drawing showing a heater system according to thepresent invention incorporated into a machine for manufacturing a setyarn froma torque stretch yarn;

FIG. 6 diagrammatically illustrates another heater system according tothe invention suitable for incorporation into a machine for processingthermoplastic textile yarns;

FIG. 7 is a detailed cross sectional view of one position'in the heatersystem illustrated in FIG. 6;

FIG. 8 is a different kind of improved heater; and

FIG. 9 is a schematic drawing ofa new type of combination machine madepossible by the use of heaters according to the invention.

The heater illustrated in FIG. 1 comprises a small metal case 10 havingan interior cavity 11. A pipe 12 is threaded into an opening in the sideof the case 10 which communicates with the cavity 11 and it is throughthis pipe so connected that plasticizing fluid under pressure isintroduced and maintained in the cavity 11. The top and bottom of thecase 10 is provided with axially aligned holes also opening into thecavity 11. Capillary seals 13 and 14 are secured to these holes. Theseals consist of capillary tubes having a very small (capillary) bore ascompared to their length. In general, in processing textile yarns of ISto 200 denier, the internal diameter of each of the seals 13, 14 shouldnot exceed one-fiftieth inch and preferably each seal .should have alength of at least about 500 times its internal diameter although thisfactor may be diminished as the internal diameter is reduced. The lowerlimit of internal diameter of the seals 13, 14 is preferably about twicethe diameter of the yarn being processed although diameters but two tofour thousandths of an inch larger than that of the yarn may be used.The effectiveness of the seal is not made to depend entirely on thediameter of the yarn passing therethrough being great enough tosubstantially occupy the whole of the cross sectional area of the seals,and therefore a small denier yarn (say 70) can be economically processedin a heater in which the internal diameter of the seals is sufficient toaccommodate a large diameter (say I00) textile yarn, although of coursethe efficiency of the heater increases as the diameters of the seals aredecreased. For this reason it is desirable that the seals 13, 14 bereadily removable so that seals may be replaced as necessary and so thatseals of different internal diameters may be used for processing yarnsof different denier under optimum conditions.

The cross sectional area of the pipe 12 which introduces plasticizingfluid under pressure into the cavity 11 is preferably larger in crosssectional area than the combined cross sectional areas of the seals 13and 14 so that the maintenance of the plasticizing fluid under pressurewithin the cavity 1 1 does not create undue turbulence within thecavity. It is also a preferable construction to flare the openings ateither end of the capillary seals so that the yarn passing therethroughdoes not strike against sharp edges. FIG. 1 illustrates a heatingelement 15 associated with the capillary seal 13 in such manner thatheat energy may be applied to the seal 13 and thus to the plasticizingfluid and yarn passing therethrough. A similar heating element can, ifdesired, be employed also in connection with the capillary seal 14 asshown in FIG. 1.

.The plasticizing fluid, which may be air, superheated steam orsaturated steam, is, at a minimum, maintained in the cavity 11 undersufficient pressure so that the fluid is forced out the distal ends ofboth seals. Preferably, when hot air is used, it is maintained in thecavity under a pressure of at least 50 to I00 pounds per square inch.The temperature of the air should, of course, be sufficiently high toaccomplish the purposes of the heat treatment. In the case of falsetwisting of nylon, for example, the temperature of the air is at leastabove the second order transition temperature and ranges up to about 465F.

The present invention makes it feasible to employ saturated steam as theplasticizing fluid and because of its dual plasticizing action, thepressure under which the steam is maintained in the cavity 11 need notbe so high as to produce a temperature equal to that which would beemployed when using hot air as the plasticizing fluid. In general, atemperature about 50 F. below the suitable hot air temperature willproduce comparable results.

The plasticizing action of the heater may be further enhanced andregulated by applying heat energy to the capillary seals as by means ofa heat element 15. When saturated steam under pressure is employed as aplasticizing fluid the heating element 15 may be adjusted so as tosuperheat the steam which is passing outwardly through the seals. Whenhot air is employed the heating element will serve to maintain the airat elevated temperatures, or to raise its temperature, as it expands andpasses outwardly through the seals. This effect is also achieved whensuperheated steam is employed as the plasticizing medium. The heater ispreferably enclosed in insulation 16.

FIG. 2 illustrates one way in which the interior walls of the capillaryseals may be modified when it is desired to use the heater in connectionwith a processing operation in which the yarn is twisting as it passesthrough the heater as for example in a false-twist operation. Theinterior walls are provided, in the form illustrated, with lands 17similar in form and purpose to rifling in a gun barrel. This contouringof the inner walls is such that it causes the plasticizing fluid passingthrough the seals to spin in the direction in which the yarn is twistingor in which it is desired to have it twist.

FIG. 3 is a schematic illustration of the use of a heater as illustratedin FIG. 1, and modified as illustrated in FIG. 2, in a false twistingmachine. Yarn Y is passed from a supply 18 through tension controllingrollers 19 and then through the heater H, the false twisting spindle 20,tension controlling rollers 21 to the windup means 22. The manner ofoperation of a machine so arranged is well known to those skilled in theart and no elaboration of its is required here. The heating systemillustrated in FIG. 3 comprises a source of plasticizing fluid underpressure 23 which may be compressed air or a suitable generator ofsaturated steam under pressure, or of superheated steam under pressure.This source is connected to a supply pipe 24 which extends the length ofthe machine with which the heater system is to be used. A suitablepressure control valve 25 and stop valve 26 may be included in thesystem. The pipe 12 of each heater is connected into the supply line 24.A stop valve 27 may be inserted in each pipe 12 in order to cut off theflow of plasticizing fluid to a particular heater. Also, each pipe 12may be provided with a heating element 28 so as to add heat energy tothe plasticizing fluid incoming to the heater H.

The heating elements 28 and 15 may be supplied from- FIG. 5 is adiagrammatic illustration of a heater syswith a machine for making setyarn from torque stretch yarn. Yarn from a supply of torque stretch yarn29 is passed downwardly through tension controlling rolls 30 through theheater H and tension controlling rolls 31 to a takeup package 32. Inthis instance, the interior walls of the seals need not be rifled orcontoured as exemplified in FIG. 2.

A further form of heater system is shown in FIG. 6, and the details ofone of its positions in FIG. 7. In lieu of employing the case and thepipe 12 leading thereto, the capillary seals 13 and 14 are mounteddirectly in vertical openings in the supply pipe 24, as may be seen inFIG. 7. Capillary seals 13 and 14 again may have heating elements suchas 15 associated therewith as well as insulation 16 as described earlierwith reference to FIG. 1. Here again the seals are preferably removable.

FIG'. 4 illustrates another form of heating element which may beassociated with the capillary seals 13, 14. This device consists of ablock of metal 33 which closely encompasses the outside walls of thecapillary seal with which it is associatedand which is capable ofserving as a heat sink. Aluminum, for example, is satisfactory in thisrespect. The block is heated to the desired temperature by means of acal-rod 34, and the block may also have embedded in it a thermostat 35which serves to regulate the heat energy supplied to the device.

In some operations, satisfactory plasticizing of the yarn may beaccomplished by simply energizing and controlling the supply of heatenergy to the heating devices (15 or 33) surrounding the capillary seals13, 14, thus providing a heater consisting of the capillary tubes of thedimensions described and means for heating them. The heating of the yarnachieved is highly efficient since the diameter of the tubes is suchthat no appreciable chimney effect exists and, as compared withpresently known heaters, a large proportion of the air which is heatedis in effective heat-exchange relationship with the yarn passing throughthe seals. A heater of this kind is obtained, for example, by closingoff the stop valve 26 to a heater H as illustrated in FIG. 3, cuttingoff the supply of energy to the heating element 27 and energizing onlythe heating elements 15 associated with the capillary seals 13, 14. Sucha simplified heater may be specially constructed, as shown in FIG. 8, bysimply wrapping a heating element such as 15 around a capillary tubehaving an inner diameter of one sixtyfourth inch and a length of 12inches and enclosing the whole in insulation such as 16. Such a heaterwill produce results comparable or superior to those obtained bypresently knownyarn heaters which are of twice the length and consumegreater quantities of energy.

It is apparent that the rate at which the yarn is traveling through anyheater and the length of the heater have a bearing on the temperature towhich the yarn is heated. In present-day false-twist machines forexample wherein the through-put of yarn may be at the rate of 120-140yards per minute, the heaters are three feet or more in length. Suchheater dimensions have necessitated special designs, including elevatedworking platform in some cases, so that the operative may properlyoversee and service the machine. A heater made according to FIG. 1, forexample, but with the capillary seals 13, 14 lengthened to 8 inches each(the overall length of the heater then being about 17 inches) willproduce results at least comparable to those attained with present dayheaters which are three feet or more in length. Furthermore, theexemplary heater also permits the economical use of saturated steamunder pressure as the plasticizing medium with further attendantadvantages.

The efficiency of the heater is such that it is now possible to design amachine which combines the making of false-twist yarn at the rate of120-140 yards per minute and the post-treating of it to make a setyarn'in a straight run (preferably downwardly) and within the overallheight of present-day machines designed merely to produce false-twistyarn alone at the stated rate. Such a combination machine is illustrateddiagrammatically in FIG. 9. It is enlightening with respect to theutility of the present invention to compare the simplicity andefficiency of this design with the awkward arrangements which heretoforehave been suggested and in some cases commercially produced as combinedfalse twisting and post treating machines. In FIG. 9, 33 represents asupply of thermoplastic yarn such as denier 34 filament nylon. The yarnpasses from the supply downwardly around the tension controlling rolis34 through the heater 11,, the false twisting spindle 35 and the tensioncontrolling rollers 36. The relative speeds of the rollers 34, 36 areadjusted to provide an overfeed of 3 percent. The heater H isconstructed in accordance with FIG. 1 as modified according to FIG. 2.The internal diameter of the capillary seals of the heater I-l is 0.01inch and each seal is 8 inches in length. The yarn passes from therollers 36 through the heater H and then to the tension controllingrolls 37 and then to the windup means 38. The speed of the rollers 37relative to the rollers 36 is such that the yarn is overfed to theheater H, by 10 percent. The heater H is of the same construction as theheater H except that the internal walls of the seals are smooth, and theseals are 0.015 inches in diameter, being made larger than those ofheater H, to accommodate the larger diameter of the partially relaxedcrimped yarn and thus avoid an undesired accumulation of yarn. Thesource of plasticizing fluid 23 is a steam generator which deliverssaturated steam at pounds gauge pressure (about 330 F.) to the heatersH, and H The energy supplied through the heating elements 15 in each ofthe heaters is adjusted so that the steam expanding in the capillaryseals is superheated. The yarn is traveled downwardly from the supply sothat greatly improved control of it is obtained as it is overfed to theheater H What I claim is:

1. A method of false twisting thermoplastic yarn plasticizing fluid isintroduced into said tube at a location and under sufficient pressure toexit said tube from both ends of said tube.

3. The method of claim 2 including the step of providing additional heatto said plasticizing fluid within said tube.

2. The method of claim 1 wherein said pre-heated plasticizing fluid isintroduced into said tube at a location and under sufficient pressure toexit said tube from both ends of said tube.
 3. The method of claim 2including the step of providing additional heat to said plasticizingfluid within said tube.